1200 New Jersey Ave. S.E.
Washington, D.C. 20590

June 5, 2008

In Reply Refer To: HSSD/B-178

Mr. Kevin K. Groeneweg
Mobile Barriers LLC
24918 Genesee Trail Road
Golden, CO 80401

Dear Mr. Groeneweg:

This letter is in response to your request for Federal Highway Administration (FHWA) acceptance of a roadside safety device for use on the National Highway System (NHS).

• Name of device: Mobile Barrier Trailer
• Type of device: Portable Work Zone Barrier
• Test Level: NCHRP NCHRP Repon 350 Test Level 2 (TL-2) or TL-3
• Testing conducted by: Southwest Research Institute
• Date of request: April 28, 2008
• Dates of follow-up: May 28, 2008 and June 3, 2008.

You requested that we find this device acceptable for use on the NHS under the provisions of National Cooperative Highway Research Program (NCHRP) Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway Features” and the proposed American Association of State Highway and Transportation Officials’ Manual for Assessing Safety Hardware – 2008 (MASH-08).

Requirements
Roadside safety devices should meet the guidelines contained in the NCHRP Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features". FHWA Memorandum “ACTION: Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers. You have also chosen to anticipate the adoption of MASH-08, an option that FHWA has offered with the understanding that additional testing may need to be done if changes to the test criteria are made before MASH-08 is formally adopted.

Description
The Mobile Barrier Trailer (MBT) is an integrated, rigid wall, semi-trailer that is used in conjunction with standard semi-tractors to provide mobile, improved, safety, and work environments for personnel at applicable maintenance, construction, and security sites. It is an extended, mobile, longitudinal barrier that provides a physical and visual wall between passing traffic and the maintenance and construction personnel. With an integrated crash attenuator at the rear, a semi-tractor at the front, and a rigid wall on the side toward passing traffic, the MBT will provide approximately 30.5 m (100 ft) of barrier and protected work area.

The basic trailer is comprised of two platforms and up to three wall sections. The platforms are each 6.4 m (21 ft) in overall length, 2.54 m (100 in) wide and 1.22 m (4 ft) high (riding approximately 1.52 m (5 ft) high with 305 mm (12 in) of ground clearance). The wall sections are each 6.10 m (20 ft) long, 610 mm (24 in) wide, and 1.22 m (4 ft) high (riding approximately 1.52 m (5 ft) high with 305 mm (12 in) of ground clearance). A homogenous 6.4 mm (0.25 in) steel plate is welded to cover the outer side of each wall section. Each wall section abuts up against another of the platforms and is built the same to take an impact from either direction. There. are no snag points at the seams. The outer 6.4 mm (0.25 in) plate and associated welds are ground beveled to transition from one to the other.

Dimensioned illustrations of the trailer are enclosed for reference as "Appendix A."

Crash Testing
One full-scale crash test was conducted using a 2329 kg Dodge, Ram quad cab pickup truck impacting at 23.5 degrees at 102.3 km/hr. The MBT deflected 0.61m (2 ft) during the jmpact. As seen in the enclosed test data summary sheet the evaluation criteria were within the limits specified in MASH-08.

Findings
Therefore, the-MBT described above and detailed in the enclosed dimensioned photographs is acceptable for use on the NHS under the range of condhions tested, when allowed by a highway agency. It will be acceptable for TL-2 or TL-3 usage depending on the test level of the Truck Mounted Attenuator that is affixed to the rear.

You subsequently requested that FHW A accept the MASH-08 Test 3-11 as indicative of the NCHRP Report 350 acceptance as well. Because the nature of the MBT device and the impact performance of the MASH-08 pickup truck we can conclude that the MASH-08 Test 10 and the NCHRP Report 350 Tests 10 and 11 can be waived. (The MBT is a semi-rigid vertical wall with relatively low friction characteristics that can be favorably compared to vertical concrete barrier walls that passed prior full-scale testing).

Please note the following standard provisions that apply to the FHW A letters of acceptance:

• This acceptance is limited to the crashworthiness characteristics of the devices and does not cover their structural features, nor conformity with the Manual on Uniform Traffic Control Devices.
• Any changes that may adversely influence the crashworthiness of the device will require a new acceptance letter.
• Should the FHWA discover that the qualification testing was flawed, that in-service performance reveals unacceptable safety problems, or that the device being marketed is significantly different from the version that was crash tested, we reserve the right to modify or revoke our acceptance.
• You will be expected to supply potential users with sufficient information on design and installation requirements to ensure proper performance.
• You will be expected to certify to potential users that the hardware furnished has essentially the same chemistry, mechanical properties, and geometry as that submitted for acceptance, and that it will meet the crashworthiness requirements of the FHWA and the NCHRP Report 350.
• To prevent misunderstanding by others, this letter of acceptance is designated as number B-178 and shall not be reproduced except in full. This letter and the test documentation upon which it is based are public information. All such letters and documentation may be reviewed at our office upon request.
• The MBT is a patented product and considered proprietary. If proprietary devices are specified by a highway agency for use on Federal-aid projects, except exempt, non-NHS projects, they: (a) must be supplied through competitive bidding with equally suitable unpatented items; (b) the highway agency must certify that they are essential for synchronization with the existing highway facilities or that no equally suitable alternative exists; or (c) they must be used for research or for a distinctive type of construction on relatively short sections of road for experimental purposes. Our regulations concerning proprietary products are contained in Title 23, Code of Federal Regulations, Section 635.411.
• This acceptance letter shall not be construed as authorization or consent by the FHWA to use, manufacture, or sell any patented device for which the applicant is not the patent holder. The acceptance letter is limited to the crashworthiness characteristics of the candidate device, and the FHWA is neither prepared nor required to become involved in issues concerning patent law. Patent issues, if any, are to be resolved by the applicant.